Grouping by powers of #x# this could be written as #color(white)("XXXX")##{: (,,+5x^6,+9x^3,,-6x), (+,-9x^7,,,-20x^2,-6x):}# #color(white)("XXXX")##"-------------------------------------------------------"# #color(white)("XXXX")##{: (" ",-9x^7,+5x^6,+9x^3,-20x^2,-12x) :}#